New wine is supersaturated with potassium bitartrate (cream of tartar). Unless sufficient quantities are removed, the bitartrate tends to deposit slowly during storage of the bottled wine causing a precipitate which is likely to be viewed by the consumer as a defect. Such wine is conventionally treated to render it, "cold stable", i.e., stable to such precipitation on storage, by first chilling the wine at temperatures from 15.degree. to 25.degree. F, depending upon the type of wine, under either continuous or intermittent circulation or holding for one week or longer, to cause some potassium acid tartrate to precipitate. Then, the cold wine is filtered to remove the precipitate to render the wine cold or tartrate stable. The above process is becoming increasingly expensive because of the high cost of energy for refrigeration.
Wine has been treated chemically for the purpose of deacidification by Boehringer Sohn. For example, many European wines are formed with an acidity on the order of 1.5% (g/100 cc of acid) or more which imparts an undesirable taste. Such wines generally include a vast excess of malic acid over tartaric acid, say, substantially greater than a ratio of 2 to 1, which accounts for the high acidity. One technique which has been employed to lower the acid content of the wine is by the addition of a calcium malate tartrate salt to the wine to precipitate malic and tartaric acid as the calcium salt from the wine. The purpose of deacidification is to significantly lower the total acid content to. say, less than 1% to render the wine more palatable. Thus, the total acidity is significantly reduced during treatment.
In general, in the technique of Boehringer Sohn the pH level of the wine is raised from about 3 to about 5.8 to favor precipitation of calcium malate tartrate. Then, this relatively high pH wine is blended back into a quantity of untreated wine to form the final product. There is no suggestion in literature supplied by Boehringer Sohn that the technique could be employed for the cold stabilization of wines which do not require deacidification.